JPH0375421B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a synthetic resin container lid having pilfer-proof properties.

[Conventional technology]

As a container lid for a container such as a beverage bottle (the outer peripheral surface of the mouth and neck of this container is formed with a male thread and a locking flange located below the male thread), No. 56-74445 discloses a synthetic resin container lid having pilfer-proof properties. The container lid has a top wall and a cylindrical skirt wall depending from the periphery of the top wall. A fracture line is formed in the skirt wall, which is composed of a plurality of slits extending in the circumferential direction at intervals in the circumferential direction and a plurality of bridge sections located between the slits, and the skirt wall is formed along the fracture line. It is divided into a main part above the break line and a pilfer-proof hem below the break line. A female thread is formed on the inner surface of the main portion, and a plurality of flap pieces protruding radially inward from the base edge connected to the inner surface of the pilfer-proof hem are formed at intervals in the circumferential direction. has been done.

[Problem to be solved by the invention]

In the conventional container lid of the above form, when the container lid is removed from the mouth and neck of the container and the mouth and neck are opened,
A problem to be solved is that the bridges at the break line are often not broken easily enough and therefore opening is not carried out easily enough. In order to solve this problem, if the strength of the bridge at the rupture line is made too low, the bridge at the rupture line will be broken when the container lid is attached to the mouth and neck of the container to seal the mouth and neck. A separate and unacceptable problem arises.

The present invention has been made in view of the above facts, and its technical problem is to prevent separate problems such as breakage of the bridge at the break line when attaching the container lid to the mouth and neck of the container. An object of the present invention is to provide an improved synthetic resin container lid in which the bridging portion at the rupture line is sufficiently easily broken when the mouth and neck of the container is opened, so that the opening can be carried out sufficiently easily.

[Means to solve the problem]

In conventional container lids, no particular attention is paid to the relative positional relationship between the bridging part of the fracture line and the flap piece formed at the hem of the pilfer-proof. In the present invention, in order to solve the above problem, each flap piece is arranged in correspondence with each bridge part, The upper end of the base edge of the flap piece is positioned in alignment with the bridge portion when viewed in the axial direction.

That is, according to the present invention, a synthetic material having pilfer-proof properties is used for a container having a neck portion in which a male thread is formed on the outer peripheral surface and a locking flange located below the male thread. The container lid is made of resin and has a top wall and a cylindrical skirt wall that hangs down from the periphery of the top wall, and the skirt wall has a plurality of slits extending in the circumferential direction at intervals in the circumferential direction, and the slits. A break line is formed with a plurality of bridging portions located between, and the skirt wall has a main portion above the break line and a pilfer-proof hem below the break line. A female thread is formed on the inner surface of the main part to be screwed into the male thread of the mouth and neck part, and a female thread is formed on the inner surface of the pilfer-proof hem. In a container lid of the type in which a plurality of locking flap pieces projecting radially inward from a base edge connected to an inner surface are formed at intervals in the circumferential direction; , and the upper end of the base edge of each of the flap pieces is positioned in alignment with each of the bridge parts when viewed in the axial direction. A container lid is provided.

[Effect]

In conventional container lids, the force that prevents the pilf-proof hem from rising, that is, the force applied from the locking flange on the neck to the flap piece at the pilf-proof hem, is the force applied to the flap piece at the pilf-proof hem. It is transmitted from the flap piece to the bridge part via the arcuate portion that exists between the flap piece and the bridge part. Therefore, part of the force transmitted from the flap piece to the bridging part is considerably reduced by the elastic deformation of the arcuate portion of the pilfer-proof hem, and due to this, the bridging part does not necessarily break easily. Nakatsuta. In contrast, in the container lid of the present invention, the upper end of the base edge of each flap piece is positioned in alignment with the bridge portion when viewed in the axial direction. Therefore, the force that prevents the pilfer-proof hem from rising is transmitted linearly from the flap piece to the bridge, so that the bridge can be reliably and easily broken.

〔Example〕

FIG. 1 illustrates one embodiment of a synthetic resin container lid with improved pilfer-proof properties in accordance with the present invention. The container lid illustrated in FIG. 1 includes a container lid body generally designated by the number 2.
The container lid main body 2, which can be formed by injection molding or embossing (compression) molding, has a circular top wall 4.
and a substantially cylindrical skirt wall 6 that hangs down from the periphery of the top wall 4. A break line 8 extending in the circumferential direction is formed in the skirt wall 6, and the skirt wall 6 is divided into a main portion 10 above the break line 8 and a pilfer-proof hem portion 12 below the break line 8. ing. The breaking line 8 includes a plurality of slits 14 that are formed at intervals in the circumferential direction and extend in the circumferential direction, and the slits 1
A plurality of bridge portions 16 remaining between the
It is composed of. The pilfer-proof hem 12 is connected to the main portion 10 by a plurality of bridging portions 16 .

The inner surface of the main portion 10 of the skirt wall 6 has a female thread 1.
8 is formed. Further, the outer surface of the main portion 10 is formed with an uneven shape or a knurled shape 20 to prevent the fingers from slipping when rotating the container lid by placing the fingers thereon.

On the other hand, the outer surface of the upper part of the pilfer-proof hem 12 of the skirt wall 6 is formed into a curved surface that gradually protrudes outward downward, and the wall thickness gradually increases downward. . A plurality of locking flap pieces 22 are formed on the inner surface of the pilfer-proof hem 12 at intervals in the circumferential direction. Each of the locking flap pieces 22 projects radially inwardly from a base edge 24 connected to the inner surface of the pilfer-proof skirt 12. As clearly shown in FIG. 2, the base edge 24 of each of the locking flap pieces 22 extends in the direction of rotation of the container lid (in FIG. In the opposite direction (clockwise as seen from above)
It extends downward while being inclined at an acute angle α with respect to the axial direction (counterclockwise when viewed from above in the figure). In addition, each of the locking flap pieces 22 is inclined in a direction opposite to the rotational direction (clockwise when viewed from above in FIG. 1) (counterclockwise when viewed from above in FIG. 1). protrudes radially inward from the base edge 24 of. The locking flap piece 22 itself has a substantially triangular shape, and its upper edge 26
extends downwardly and radially inwardly at a slight angle β, and its lower edge 28 extends upwardly and radially inwardly at a considerable angle γ, for example 60 degrees. There is. The angle β is determined by the fact that the locking flap piece 22 is elastically deflected along its base edge 24 in the opposite direction (counterclockwise in FIG. 1) with respect to the rotational direction (clockwise in FIG. 1). Advantageously, the upper edge 26 is set to be substantially horizontal when one side of the locking flap piece 22 is in contact with the inner surface of the pilfer-proof hem 12.

FIG. 3 shows another embodiment of the locking flap piece. Locking flap piece 122 shown in FIG.
, its base edge 124 extends substantially parallel to the axial direction. It projects radially inwardly from the base edge 124 without being inclined, and therefore substantially perpendicularly to the inner surface of the pilfer-proof hem 12 . The upper edge 126 of the locking flap piece 122 extends radially inwardly in a substantially horizontal manner. Since the locking flap piece 122 illustrated in FIG. The piece 122 is elastically deflected along its base edge 124 in the opposite direction (counterclockwise when viewed from above in FIG. 1) with respect to the rotational direction (clockwise when viewed from above in FIG. 1). However, upper edge 1
26 extends substantially horizontally.

Therefore, in the container lid improved according to the present invention, the above-mentioned locking flap piece 22 (or 12
It is important that each of 2) is arranged corresponding to each of the bridges 16 at the break line 8 formed in the skirt wall 6. For more details,
A locking flap piece 22 (or 122) is disposed corresponding to each of the bridging parts 16 at the breaking line 8, and each of the locking flap pieces 22 (or 122) corresponding to each of the bridging parts 16 The upper ends of the proximal edges 24 (or 124) of are positioned substantially in alignment with each of the bridges 16 when viewed in the axial direction;
In other words, the base edge 24 of each of the locking flap pieces 22 (or 122) corresponding to each of the bridge portions 16
(or 124) downwardly (inclined at an acute angle α to the axial direction or substantially parallel to the axial direction) from a position substantially aligned with each of the bridge sections 16 when viewed in the axial direction. It is important that it is extended.

In the embodiment shown in FIGS. 1 to 3, all of the plurality of flap pieces 22 (or 122) are arranged corresponding to the plurality of bridge portions 16 at the breaking line 8. Therefore, the number of flap pieces 22 (or 122) and the number of bridging parts 16 are the same. However, if desired, in addition to arranging the same number of flap pieces 22 (or 122) as there are bridges 16 in correspondence with each of the plurality of bridges 16, It is also possible to attach the flap piece 22 (or 122) to an additional flap piece 22 (or 122) that does not have the above-mentioned relationship with any of the above but is located between the bridge parts 16 in the circumferential direction.

FIG. 4 illustrates another embodiment of flap pieces provided corresponding to each of the bridges in the break line. In the embodiment shown in FIG. 4, each flap piece 222 extends axially upward and is connected to the main body 10 at its upper end. That is, in the embodiment shown in FIG. For example, the bridging portion 216 also defines a portion of the flap piece 222, ie, the upper end).

In the known synthetic resin container lid of the type in which a plurality of locking flap pieces are formed at intervals in the circumferential direction on the inner surface of the pilfer-proof hem, the bridging portion at the rupture line and No particular consideration was given to the relative relationship with the locking flap pieces, and each of the plurality of locking flap pieces had its base edge located at an appropriate position between the bridge portions in the circumferential direction. was located so that According to the experience of the present inventors, in such known synthetic resin container lids, when the container lid that is attached to the mouth and neck of the container as required is removed from the mouth and neck and the mouth and neck are opened, However, there has been the problem or drawback that the bridge at the break line is not often broken easily enough and therefore opening is not easily accomplished enough.

On the other hand, the flap piece 22 (or 122, 22
According to the container lid improved according to the present invention, which is provided with 2), when the container lid attached to the mouth and neck of the container as required is removed from the mouth and neck and the mouth and neck are opened. is the bridge portion 16 at the fracture line 8
(or 216) is sufficiently easily and reliably broken;
Opening can therefore be carried out quite easily.

Furthermore, a plurality of bridge portions 1 at the fracture line 8
The improved container lid according to the invention, in which the flap pieces 22 (or 122, 222) are arranged in association with each of the flaps 6 (or 216) as described above, also provides the following advantages: It will be done. That is, the container lid body 2 is formed by injection molding or embossing (compression) as described above.
It can be formed by molding, but during such molding, the synthetic resin material is generally in a softened state.
It flows from the central part of the top wall 4 to the peripheral part, then flows to the main part 10 of the skirt wall 6, and then flows to the pilfer-proof hem 12 through the bridging part 16 (or 216). However, as described above, the flap pieces 22 (or 12
2, 222), the softened synthetic resin material flows directly to the flap piece 22 (or 122, 222) through each of the plurality of bridge parts 16 (or 216). , this promotes material flow to the entire pilfer-proof hem 12 and also allows the flap piece 22 (or 122, 22
2), the material flows reliably, and thus the container lid main body 2 can be reliably injection-molded or embossed (compressed) molded into the desired shape at a sufficiently high speed.

The container lid shown in FIG. 1 includes, in addition to the container lid main body 2 described above, a packing member 30 disposed on the inner surface of the top wall 4 of the container lid main body 2. The packing member 30 is made of a synthetic resin material different from the synthetic resin material forming the container lid body 2. When the container lid body 2 and the packing member 30 are made of a separate synthetic resin material, the container lid body 2 is made of a relatively hard synthetic resin material such as polypropylene or hard polyethylene, and the packing member 30 is made of polychloride. Conveniently, it is formed from a relatively soft synthetic resin material such as vinyl, ethylene vinyl acetate or flexible polyethylene.

Packing member 30 in the illustrated embodiment is generally disc-shaped and has a substantially flat lower surface. On the other hand, on the inner surface of the top wall 4 of the container lid main body 2, a disk-shaped protrusion 31 exists in the central circular area, and therefore, the annular peripheral area is recessed. The upper surface of the packing member 30 is made to match the inner surface of the top wall 4 of the container lid body 2, so that the packing member 30 has an increased wall thickness in its annular peripheral region. Such a packing member 30 is produced by, for example, loading a synthetic resin material in a heated and molten state onto the inner surface of the top wall 4 of the container lid body 2 that has already been molded, and then stamping (compressing) the synthetic resin material into a desired shape. ) can be conveniently formed by moulding.

Therefore, when the packing member 30 is formed from a synthetic resin material separate from the container lid body 2 as described above, the packing member 30 is not sufficiently bonded to the inner surface of the top wall 4 of the container lid body 2, and therefore There is a tendency for the packing member 30 to move downward or rotate about the axis with respect to the inner surface of the top wall 4. If it is desired to prevent such a tendency, a packing member 3 is installed on the inner surface of the top wall 4.
0, spray paint an appropriate adhesive on the inner surface of the top wall 4, as shown schematically in FIG. It is also possible to dry the adhesive using a heater 32 such as an infrared heater, and then emboss (compress) the adhesive onto the inner surface of the top wall 4. In this way, the packing member 30 can be adhered to the inner surface of the top wall 4 with sufficient reliability by the action of the adhesive. If it is undesirable for the adhesive to adhere to the inner surface of the top wall 4 covered by the packing member 30, for example, to the inner surface of the skirt wall 6, as shown briefly in FIG. When spraying adhesive from the top wall 4 toward the inner surface of the top wall 4, make sure that the tip
A cylindrical shielding member 36 may be positioned around the spray head 34 so as to abut the inner and outer peripheral edges of the spray head.

A container closure as described above is applied to a container with a conventional neck as shown at 38 in FIG. The mouth and neck portion 38 having an open upper end has a substantially cylindrical shape, and a male thread 40 and a locking flange 42 located below the male thread 40 are formed on its outer peripheral surface. The circumferential side of the locking flange 42 is inclined downwardly and radially outward, and the locking flange 4
A substantially horizontal annular locking surface 44 is defined on the lower surface of 2.

To seal the mouth and neck part 38 by attaching the container lid to the mouth and neck part 38, the container lid is fitted onto the mouth and neck part 38, and the container lid is rotated clockwise when viewed from above in FIG. In this way, the female thread 18 formed on the container lid is screwed into the male thread 40 formed on the neck portion 38, thereby causing the container lid to move downward in the axial direction as it rotates. When the container lid is moved downward, the locking flap piece 22 (or 122, 222) formed on the container lid
passes through the male thread 40 formed on the neck portion 38 and then passes through the locking flange 42, but at this time, the locking flap piece 22 (or 122, 222) is not locked. Under the action of the flange 42, the locking flap piece 22 (or 12) is elastically deflected in a counterclockwise direction when viewed from above in FIGS.
2, 222) can pass through the locking flange 42. When the female thread 18 of the container lid and the male thread 40 of the neck part 38 are fully screwed together and the container lid is fully attached to the neck part 38 as shown in FIG.
The locking flap piece 22 (or 122, 222) completely passes through the locking flange 42 and locks into the locking flange 4.
It is no longer affected by the effects of 2 and elastically returns to its original state. In this way, the locking flap piece 22 (or 1
The upper edge 26 (or 126) of the locking flange 42 is locked to an annular locking surface 44 defined on the lower surface of the locking flange 42. Further, when the container lid is fully attached to the neck part 38, as shown in FIG.
8, and the mouth and neck 38 are thus sealed.

When the container lid attached to the mouth and neck part 38 is detached from the mouth and neck part 38 as described above and the mouth and neck part 38 is opened, the container lid is rotated in the direction opposite to the direction of rotation when the container lid is attached, that is, in the seventh direction. Rotate counterclockwise when viewed from above in the figure. In this way, the female thread 18 formed on the container lid is moved along the male thread 40 formed on the neck portion 38, so that the container lid does not move upward in the axial direction. However, the upper edge 26 (or 1
26) is locked to the annular locking surface 44 defined on the lower surface of the locking flange 42 of the mouth and neck portion 38, so that the pilfer-proof hem 12 is prevented from moving upward in the axial direction. Significant stress is thus created in each of the bridges 16 (or 216) at the break line 8 formed in the container lid, connecting the pilfer-proof skirt 12 to the main portion 10 of the skirt wall 6. Bridge section 16 (or 21
6) is broken.

Thus, in the container lid improved according to the present invention, as described above, each of the locking flap pieces 22 (or 122, 222) is connected to each of the bridge portions 16 (or 216) at the breaking line 8. It is arranged in relation to Figure 2 (or Figure 3, Figure 4).
As clearly shown in FIG.
(or 122, 222), the upper end of each base edge 24 (or 124) is connected to the bridge portion 16 when viewed in the axial direction.
(or 216). In other words, the locking flap piece 22 (or 1
22, 222) each base edge 24 (or 124)
The upper end of each of the bridge portions 16 (or 216) is located directly below the bridge portion 16 (or 216) at the fracture line 8 in the axial direction. Therefore, as will be readily understood by referring to FIG. 7 in conjunction with FIG. force, i.e. from the annular locking surface 44 of the locking flange 42 to the locking flap piece 22.
(or 122, 222) upper edge 26 (or 126)
The force applied to the bridge section 16 (or 2
16), and therefore the bridge portion 16 (or 216) is ruptured reliably and with sufficient ease.

On the other hand, in known container lids, as described above, the relative relationship between the bridge portion and the locking flap piece at the break line is not considered, and the upper end of the base edge of the locking flap piece is aligned with the axis. When viewed in the direction, the bridge is offset from the bridge at the rupture line. Therefore, the force that prevents the pilfer-proof hem from moving upward in the axial direction, that is, the force applied from the annular locking surface of the locking flange to the upper edge of the locking flap piece, is transmitted to the bridging part via the portion between the bridging part and the locking flap piece when viewed in the circumferential direction. In such a case, the force transmitted from the locking flap piece to the bridging portion is absorbed and reduced by the elastic deformation of the portion of the pilfer-proof hem portion that exists between the two. Therefore, the bridges tend not to break easily enough and the opening operation to be accomplished not easily enough.

Bridge portion 16 (or 21
6) is broken, the pilfer-proof hem 1
2 is separated from the main part 10 of the skirt wall 6. After that, the portion of the container lid other than the pilfer-proof hem 12 can easily move upward in the axial direction, and therefore moves upward in the axial direction in accordance with the rotation of the container lid to close the neck portion 38. The mouth and neck region 38 is thus opened. On the other hand, the pilfer-proof hem 12 has a mouth and neck area 38.
remain there without being removed from it.

FIGS. 8 and 9 illustrate yet another embodiment intended to increase the sealing of the mouth and neck portion 38 by means of a packing member 30 that is brought into close contact with the end surface 46 of the mouth and neck portion 38.

In the embodiment shown in FIG. 8, two annular supporting protrusions are provided in the annular peripheral area on the inner surface of the top wall 4 of the container lid body 2, that is, in the annular peripheral area facing the end surface 46 of the neck part 38. An outer annular support ridge 48 and an inner annular support ridge 50 are formed. The outer annular support ridge 48 is attached to the end surface 4 of the mouth and neck portion 38.
6, and the inner annular support protrusion 50 is located opposite to the inner circumference of the end surface 46 of the mouth and neck portion 38. Due to the presence of the outer annular support ridge 48 and the inner annular support ridge 50, the packing member 30 has two annular regions (i.e., the outer annular support ridge 48 and the inner annular support ridge 50).
The wall thickness is locally reduced in areas where

The embodiment shown in FIG. 8 as described above has the following advantages over the container lid shown in FIG. have In the container lid shown in FIG.
The end face 46 is substantially uniform over the entire area from the inner circumferential edge to the outer circumferential edge. Therefore, from the container lid to the mouth and neck 3
The pressure applied to the end surface 46 of the mouth and neck portion 38 is substantially uniformly distributed over the entire area of the end surface 46 of the mouth and neck portion 38 .
On the other hand, in the embodiment shown in FIG. The contact pressure with the end surface 46 becomes locally high. To explain this point in more detail, as already mentioned, the container lid body 2 is generally made of a relatively hard synthetic resin material, and the packing member 30 is made of a relatively soft synthetic resin material. Therefore, packing member 3
When the lower surface of the packing member 30 is elastically compressed between the top wall 4 of the container lid body 2 and the end surface of the neck part 38, a relatively hard The outer annular support ridge 48 and the inner annular support ridge 50, which are made of a synthetic resin material, locally back up the packing member 30, and thus the packing member 30 is formed from the outer annular support ridge 48 and the inner annular support ridge 50. Article 50
The two annular regions where the
8 and is brought into close contact with the end surface 46 of 8. In this way, when the contact pressure between the lower surface of the packing member 30 and the end surface 46 of the mouth and neck section 38 is locally increased in a predetermined annular region, the pressure applied from the container lid to the end surface 46 of the mouth and neck section 38 increases. A considerable contact pressure is generated in the predetermined annular region, thus increasing the sealing of the neck region 38 by the packing member 30, and the contents of the container are able to contain carbonated beverages. etc., and even if considerable pressure is generated within the container, sufficient sealing performance can be obtained.

In the embodiment shown in FIG. 9, in addition to the above-described outer annular support ridge 48 and inner annular support ridge 50 being formed on the inner surface of the top wall 4 of the container lid body 2, The circumferential wall surface of the disc strip protruding portion 31 existing in the center area of the inner surface of the top wall 4 is projected toward the inner circumferential edge of the end surface 46 of the mouth and neck portion 38, as indicated by reference numeral 52. In such an embodiment, in addition to the two annular regions corresponding to the outer annular support ridge 48 and the inner annular support ridge 50, that is, the outer and inner peripheries of the end surface 46 of the neck portion 38, the disc Due to the protrusion of the circumferential wall surface of the strip projection 31, the contact pressure between the lower surface of the packing member 30 and the end surface 46 of the mouth and neck portion 38 is locally increased also at the inner peripheral edge of the end surface 46 of the mouth and neck portion 38. .

10 and 11 show the locking of the packing member 30 to the inner surface of the top wall 4 of the container lid body 2;
That is, a further embodiment is shown for preventing the packing member 30 from moving downwardly and rotating about its axis.

As described above, the packing member 30 is constructed by filling the inner surface of the top wall 4 with a synthetic resin material in a heated and molten state after molding the container lid main body 2, and then pressing and molding the synthetic resin material into a desired shape. It can be conveniently formed by. However,
It is often desirable to reliably prevent the packing member 30 from moving downward or rotating about the axis relative to the inner surface of the top wall 4 of the container lid body 2; 4
If the packing member 30 is simply stamp-molded on the inner surface of the top wall 4, the packing member 30 is generally not sufficiently bonded to the inner surface of the top wall 4, and the above requirements cannot be fully satisfied. As a solution to this problem, as explained with reference to FIGS. 5 and 6, a suitable adhesive is applied to the inner surface of the top wall 4 before stamping the packing member 30. The adhesive can then be allowed to dry if desired. However, such solutions create separate problems, such as the additional step of applying (and drying) the adhesive, which increases the manufacturing cost of the container lid. .

In the embodiment shown in FIGS. 10 and 11, a plurality of engagements extending in the radial direction are provided on the inner surface of the top wall 4 of the container lid body 2 (for example, the surface of the disc strip protrusion 31). Stop grooves 54 are formed at intervals in the circumferential direction. Each of the locking grooves 54
As shown in the figure, it is preferable to have a trapezoidal cross-sectional shape in which the width gradually increases toward the bottom. When the packing member 30 is molded by stamping on the inner surface of the top wall 4 in which such a locking groove 54 is formed, as can be easily understood from FIG. A locking projection 56 is correspondingly formed. In this way, the packing member 30 is locked to the inner surface of the top wall 4 by the mutual engagement of the locking groove 54 and the locking protrusion 56, and the packing member 30 is moved downward with respect to the inner surface of the top wall 4. or rotation about the axis is reliably prevented. Instead of forming the locking groove 54 on the inner surface of the top wall 4, a locking projection is formed, and the packing member 30 is inevitably formed with a locking groove corresponding to the locking projection. It is also possible to obtain similar effects.

Therefore, the locking groove 54 (or locking protrusion) formed on the inner surface of the top wall 4 may have a ring-shaped or chord-shaped shape, for example, instead of extending in the radial direction. When a locking groove (or locking protrusion) is formed in this manner, the following problems occur. That is, when the synthetic resin material in a heat-softened state is loaded onto the inner surface of the top wall 4 and the packing member 30 is then molded by stamping, the synthetic resin material is made to flow in the radial direction on the inner surface of the top wall 4. However, if a locking groove (or locking protrusion) other than that extending in the radial direction is formed on the inner surface of the top wall 4, the locking groove (or locking protrusion) may cause the synthetic resin material to Smooth flow is obstructed.

〔Effect of the invention〕

In the container lid improved according to the present invention,
The bridge at the break line can be easily opened when opening the neck of the container without causing problems such as the bridge at the break line being broken when attaching the container lid to the neck of the container. is broken, so that opening can be carried out with sufficient ease.

[Brief explanation of drawings]

FIG. 1 is a side view, partially in cross section, of an embodiment of a synthetic resin container lid having improved pilfer-proof properties according to the present invention. 2 is a perspective view showing a part of the container lid of FIG. 1; FIG. 3 and 4 are perspective views similar to FIG. 2, respectively, showing other embodiments of the locking flap piece. 5 and 6 are simplified cross-sectional views illustrating, respectively, an adhesive spray coating process and a drying process that may be performed in manufacturing the container lid of FIG. 1; FIG. 7 is a side view, partially in cross section, of the container lid shown in FIG. 1 attached to the mouth and neck of the container. FIG. 8 and FIG. 9 are partial cross-sectional views showing modified examples intended to increase sealing performance, respectively.
FIG. 10 is a sectional view showing a modified example of locking the packing member to the inner surface of the top wall. FIG. 11 is a partial sectional view taken along line XI-XI in FIG. 10. 2... Container lid main body, 4... Top wall, 6... Skirt wall, 8... Breaking line, 10... Main part of skirt wall, 12... Pilfer-proof hem, 14
...Slit, 16 and 216...Bridge part, 2
2, 122 and 222...locking flap piece, 24
and 124... base edge of locking flap piece, 30...
Packing member, 38... Mouth and neck portion, 48... Outer annular support ridge, 50... Inner annular support ridge, 54
...Latching groove, 56...Latching protrusion.

Claims (1)

[Scope of Claims] 1. A synthetic resin having pilfer-proof properties for a container having a neck portion in which a male thread and a locking flange located below the male thread are formed on the outer peripheral surface. The container lid has a top wall and a cylindrical skirt wall hanging from the periphery of the top wall, and the skirt wall has a plurality of slits extending in the circumferential direction at intervals in the circumferential direction, and a plurality of slits extending in the circumferential direction at intervals in the circumferential direction. A break line is formed by a plurality of bridges located at A female thread is formed on the inner surface of the main portion to be screwed into the male thread of the mouth and neck portion, and an inner surface of the pilfer-proof hem is formed on the inner surface of the pilfer-proof hem. In a container lid of the type having a plurality of circumferentially spaced locking flap pieces projecting radially inwardly from a base edge connected to the bridging portion; and wherein the upper end of the base edge of each of the flap pieces is positioned in alignment with each of the bridge parts when viewed in the axial direction. lid. 2. A container lid according to claim 1, wherein the base edge of each of the locking flap pieces extends substantially parallel to the axial direction. 3. The base edge of each of the locking flap pieces extends downward at an acute angle with respect to the axial direction in a direction opposite to the direction of rotation of the container lid when the container lid is attached to the mouth and neck. A container lid according to claim 1. 4. Each of said locking flap pieces projects radially inwardly from said base edge substantially perpendicular to the inner surface of said pilfer-proof hem.
The container lid described in any of Items 1 to 3. 5. Claims in which each of the locking flap pieces projects radially inward from the base edge at an angle opposite to the direction of rotation of the container lid when the container lid is attached to the mouth and neck. The container lid according to any one of paragraphs 1 to 3.